As a conventional switchgear having a pressure discharge plate, for example, a switchgear is disclosed in which: a main circuit apparatus chamber containing withdrawable breakers individually, which are piled at multiple stages in the vertical direction, and a control apparatus chamber are arranged in the right-left direction on the front side of a housing made of grounded metal; a common pressure discharge duct chamber extending in the vertical direction is provided in back of the control apparatus chamber; in back of these, a vertical bus chamber, a current transformer chamber, a horizontal bus chamber, and a cable chamber are provided; the above chambers are partitioned by partition walls; and among the partitioned chambers, except the horizontal bus chamber, partitioned chambers contacting a ceiling portion have pressure discharge plates at the ceiling portion, and partitioned chambers not contacting the ceiling portion are linked with the common pressure discharge duct chamber which has a pressure discharge plate at the ceiling portion (see Patent Document 1).
In addition, for example, an enclosed switchboard is disclosed in which: the inside of the board housing is partitioned into breaker chambers and cable chambers at upper and lower stages and a main bus chamber, which are separated from each other by partition walls; exhaust ducts extending in the vertical direction are provided at the center and the back of the inside of the board housing; an apparatus chamber provided at the upper stage has an exhaust opening directly on a ceiling; the breaker chamber at the lower stage, the cable chamber at the lower stage, and the main bus chamber communicate with the ceiling side through the exhaust ducts, and are provided with respective exhaust openings on the ceiling; and each exhaust opening has a pressure discharge plate (see Patent Document 2).